Considerations for Post Bag Robot Design

FIRST General Forum
1

With kickoff less than a month away, I would hope many teams have had discussions about how they’re going to handle the 2020 season now that the bag is gone. I’m sure there have been many conversations about schedules… maybe a more relaxed schedule, maybe you’re keeping it the same, maybe you’re planning on completely rebuilding your robot after the competition season begins… Regardless of what direction your team is going, I would think build season schedules would be pretty well thought out by most teams at this point.

One important consideration that must be made in a post bag world, that might not be obvious, is robot design. Teams that have only ever built one robot will now have the opportunity to put many more hours of practice in. Some teams that historically built two robots will now only build one robot. In all cases, robots will undergo a lot more wear than they have in previous years.

If you’ve only ever built one robot before, ask your nearest team that builds two how their practice bot holds up towards the end of the competiton season… FRC robots, for a lot of teams, have historically been designed for hours of use, not hundreds of hours of use. Many commonly used components will break down with extended use, especially in cases where components are pushed to their limits, or used improperly.

There are some choices that teams can make that will reduce the impact that the extended practice time has on robot performance, and lifespan.

When you show up for your event, you want your robot to be broken in, but not broken down. What I mean by this is that there is a sweet spot for robots when they’ve been driven enough that their mechanisms are running smoothly but the robot isn’t experiencing wear and tear. Just like an athlete needs to warm up before a game, your robot should be run in before an event.

Pay attention to the proper use guidelines for purchased components. In the past, many teams have gotten away with using a versaplanetary gearbox outside of its rated limit. Those types of applications are much more likely to result in failure with extended use. It’s also worth considering spring assisting heavy loads anywhere on your robot that pushes gearboxes and other COTS mechanisms to work hard.

Identify your wear parts, keep them in stock, and keep a close eye on them. As you’re driving your robot, you should take note of what parts need to be swapped out, and what regular maintenance is required for your robot to stay on the practice field. You can learn a lot from documenting your failures, and now with no bag, you can redesign systems that are prone to failures. For parts that regularly need to be swapped out, (wheel tread, intake wheels etc.) make sure you have enough in stock to keep your robot functioning.

Ultimately the goal is for teams to be able to enter an event, pass inspection, and get on the practice field as soon as possible. No more using your first two matches to break your robot in and learn its failure modes.

I’m curious to hear what other robot design considerations teams will be making in the post bag era. Maybe you’re choosing to use steel gears over aluminum gears. Maybe you choose to use chain over belt or vice versa. What robot design considerations will your team make for the 2020 season that differs from previous years?

34 Likes
2

Neutral buoyancy is always a goal of good mechanical design, for lots of reasons. Sometimes you just can’t do it, but when you can, you should.

Modularity. Depending on the challenge, we want to be able to easily swap mechanisms if necessary, so designing for common mounting points and so forth; anything to make that kind of switch faster and easier.

We already use steel gears over aluminum, having learned that lesson the hard way. Well-built belt (or even strap) systems shouldn’t have an issue with even thousands of hours of wear, so I’m not terribly worried on that score.

I might double the number of batteries we buy for the season…

5 Likes
3

@Ryan_Swanson, totally agree with the concerns you raise. Having mentored a team which did a “working prototype” robot in the third year, and a real “practice robot” starting the next year, but which had quite limited practice time before bag except the low-stress 2015, and only did one official event per year (again, except 2015), wear and tear on the competition robot was not an issue. These things are much more likely to become issues for teams which scale back to a single robot.

What concerns me more than robot design, though, is time/season management. There’s a good bit more time to manage or mismanage, especially if you’re competing past about week 2. I encourage team leaders to seriously think about and plan for how to manage that time.
If you slowed way down after bag day, perhaps shaving off a few hours from each week will help you go the distance.
If you kept going at [nearly] the same pace after bag day, you probably don’t need to cut hours, but you do need to figure out how much of your “second/third robot” effort from previous years is/is not worth doing when weighed against @Ryan_Swanson’s post.

@pfreivald, I don’t see how the concerns you’ve raised reflect post-bag, except the increase in batteries. Please elucidate.

4

More time on stick = more wear and tear = more spare parts that need to be swapped. Having modular complete mechanisms means you can swap things off very quickly and get back to business, rather than having extended down time for repair. It’s smart in general, but it’s even more smarter-er now.

5

Oh, I read modular as meaning that you could swap for different mechanisms. Interchangeable mechanisms, yes!

6

I kind of meant it both ways, but mostly the one way.

7

The main thing I’m hammering into my team is how much more the meta game will develop during the competition season. Now more than ever we will need to keep improving between competitions

8

We currently have one full weight and height robot running (2019), and two functional drive bases with different measurements. Barring something crazy, we will use the basic measurements of one of the two drive bases as the foundation of our 2020 robot and create superstructure that can be mounted on it and then moved to the competition robot once tested. We’re only building one full robot, but will have these existing bases to help with development and drive practice. This is quite a change from the past 6 years but we hope it will make thing easier and quicker.

9

I think what teams also have to realize is that they still need to stay within their limits. Having more time doesn’t necessarily equate to being able to do more. It’s more like you now have a bigger buffer so you can experiment more but remember your limits.

An idea I think might work is like you set a goal and then there’s an advanced version of that goal. The goal is within In your limits and the advanced isn’t so you can complete your goal and if time remains, work in the advanced portion but you always have the original to fall back on.

1 Like
10

The technical term for this is a “stretch goal”, and it’s definitely a thing. I think that’s definitely a great way for a team to operate in any year, but especially applicable with no bag.

Designing within your limits is something that a lot of people preach every year and it’s always going to be true… I do have some concern that the perceived “extra time” will make people throw a lot of that out. The teams that stay true to their processes from previous years, and treat the “extra time” as actual extra time will have the most success.

1 Like
11

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.